The medical and supply relief division of the Gotei 13, the fourth division have a reputation for weakness in comparison to other squads. Indeed, their focus is on kidou and related healing arts rather than combat, though they are by no means defenceless. Lower-ranked members of the 4th division are often victimised by members of other squads – particularly the warlike 11th division – if the opportunity arises.
Captain: Unohana Retsu
Xaptain Unohana is a mature, middle-aged woman who is soft-spoken, polite, and caring. She uses honourifics when addressing everyone, including her subordinates, and rarely shows panic or distress. Despite her calm, motherly demeanour and meticulously polite speech, however, there is something unerringly terrifying about Unohana when she wishes it, something which is not lost on low-ranking shinigami.
Fitting with her personality, Unohana wears the standard shinigami captain's uniform, but her most notable physical feature is that she wears her long black braid in front of her neck rather than the back.
Zanpakutou: Minazuki (lit. "Purify the Flesh")
In sealed form, Minazuki is slightly longer than ordinary katana, and resembles a nodachi. Instead of tying it to her obi, Unohana carries her zanpakutou over her shoulder by a rope strap or lets Isane carry it for her. When unsealed, Minazuki transforms into a giant, flying, one-eyed creature which resembles a manta ray. It's large enough to transport many people on its back (at least a dozen). Additionally, it can swallow even more people and transport them in its stomach, healing their injuries at the same time. When Unohana reseals Minazuki, it dissolves into green mist and reforms into the sheath of her zanpakutou.
Vice-captain: Kotetsu Isane
Vice-Captain Kotetsu is a generally quiet and observant young woman, extremely tall and somewhat mannish in her build, with pale hair worn short except for two stray tails. She would generally be described as "handsome", though her shyness makes her seem a little awkward. More physically adept than most members of the 4th division, Isane seems to be pursuing the role of a protector as much as a healer, and looks to Unohana as a mentor and mother figure. It is noted by Unohana that Isane suffers from frequent and recurring nightmares, though this is not particularly common knowledge to other shinigami outside the 4th division.
Zanpakutou: Itegumo (lit. "Frozen Cloud")
Its guard is shaped like a snowflake, but it otherwise appears as a normal katana when sealed. Its shikai command is "sprint". When its shikai is activated, two smaller blades protrude from Itegumo's hilt at 45° angles, but beyond this its special abilities are unknown.